Tutorials

Tutorial 1 - Monday 22 May, 2006 - 9:00 - 13:00

Wireless Mesh Networks: Fundamentals, Basic Protocols and Research Issues

Instructors:
Samir R. Das (State University of New York at Stony Brook)
Prasant Mohapatra (University of California, Davis)
W. Steven Conner (Intel)

Abstract:

Wireless mesh networks are multihop networks of wireless router platforms. The wireless routers are typically stationary, but the clients and some routers can be mobile. A mesh network can provide multihop communication paths between wireless clients serving as an outdoor community network or broadband access network for the Internet or an indoor home or office network. Wireless mesh networks are considered cost-effective alternatives to traditional wireless LANs, as there is no necessity to deploy any wired infrastructure to support a mesh network. With the plummeting cost of 802.11-based hardware platforms, wireless mesh networking is gaining ground with several industry players developing 802.11-based mesh networking platforms and services. Large-scale, metropolitan wide mesh networks are also planned.
There are several technical challenges that must be addressed for mesh networking to be as effective as any other form of broadband networking. Much of these challenges relate to multihop wireless communication and limited capacity. This tutorial is designed to introduce essential mesh networking concepts, lay down the technical challenges and describe how the research community is addressing them. We will explore the issues associated to each layer of the protocol stack as well as various cross-layer approaches. In the link layer, we will describe multiple access protocols for multihop networks, including IEEE 802.11 and address its limitations. We will describe various approaches to build capacity including use of multiple channels and multiple radios, directional antennas and transmit power control. In the routing layer, we will cover multihop routing and routing metric issues. In the transport layer, we will address TCP performance for multihop wireless networks. We will also discuss several issues of recent interest that span all layers, including multihop capacity and fairness.

The other tutorial related to mesh networks will complement this tutorial by focusing on practical deployment issues and covering applications, testbeds, products and standards.

Intended Audience

The tutorial will benefit attendees from both industry and academia who are interested in the core challenges in wireless mesh networking and the current state of the art in this field. Basic understanding of computer networking is required to benefit fully from the tutorial.

Biographies of Instructors

Samir R. Das is currently an Associate Professor in the Computer Science Department in the State University of New York at Stony Brook. He received his Ph.D. in Computer Science from Georgia Institute of Technology, Atlanta, in 1994. His research interests include wireless multihop networking, performance evaluation and parallel discrete event simulation. He has more than sixty refereed research articles on these topics. Samir Das has received the U.S. National Science Foundation's CAREER award in 1998. He has been a speaker in the Distinguished Visitor program of the IEEE Computer Society during 2001-03. He co-chaired the program committee for the ACM MobiHoC Symposium in 2001 and ACM MobiCom Conference in 2004. He serves on the editorial board of the IEEE/ACM Transactions on Networking, IEEE Transactions on Mobile Computing, ACM/Kluwer Wireless Networks Journal and the Ad Hoc Networks journal.

Prasant Mohapatra received his Ph.D. in computer engineering from the Pennsylvania State University in 1993. He was an assistant professor and then an associate professor at Iowa State University from 1993 to 1999, and then at Michigan State University till 2001. Since then he has been at University of California, Davis, where he is currently a Professor in the Department of Computer Science. Dr. Mohapatra has published extensively in various international journals and conferences. He has been an invited speaker at several universities and other organizations in several countries. He has given several tutorials in various international venues, and has taught several advanced courses in computer networks, wireless networks, performance evaluation, and multimedia systems. His research work has been funded and collaborated by National Science Foundation, SIEMENS, EMC Corporation, Panasonic Technologies, Hewlett Packard, Rockwell International, and Intel Corporation. He was/is on the editorial board of the IEEE Transactions on computers, ACM WINET, and Ad Hoc Networks. He has been on the program/organizational committees of several international conferences. He was the Program Vice-Chair of INFOCOM 2004 and MASS 2004, and the Program Co-Chair of the First IEEE International Conference on Sensor and Ad Hoc Communications and Networks (SECON 2004). He is also the Co-Chair of the First IEEE Workshop on Wireless Mesh (WiMesh 2005). He has been a Guest Editor for IEEE Network, IEEE Transactions on Mobile Computing, and the IEEE Computer.

W. Steven Conner is a Wireless Network Architect in the Communications Technology Lab, Intel Corporate Technology Group. He has been with Intel since 1999 and currently leads a team developing self-configuring wireless mesh networking technology. Steven is the Technical Editor of the IEEE 802.11s Mesh Networking standard and is an active participant in IEEE 802.11 standards development. His current research interests include wireless mesh networking, sensor networks, and network self-configuration protocols. He received B.S. and M.S. degrees from the University of Arizona.

Tutorial 2 - Monday 22 May, 2006 - 14:00 - 18:00

Wireless Mesh Networks: Applications, Testbeds, Products and Standards

Instructors:
Samir R. Das (State University of New York at Stony Brook)
Prasant Mohapatra (University of California, Davis)
W. Steven Conner (Intel)

Abstract:

This tutorial will introduce essential mesh networking concepts with a focus on practical deployment issues. We will focus on various applications of mesh networking such as home networking, enterprise networking, last-mile and community networking. We will describe various academic and industry research lab testbeds for experimental studies in mesh networks and lessons learnt from these testbeds. We will address technical issues such as QoS, security, network management and monitoring. We will cover various mesh networking related industry products and services. Finally, we will address standardization efforts in IEEE 802.11s ESS Mesh working group. We will end with comments of future of mesh networking, including impact of other emerging technology such as WiMax.

Intended Audience

same of above

Biographies of Instructors

same of above

Tutorial 3 - Monday 22 May, 2006 - 9:00 - 13:00*****CANCELED*****

Pervasive Environments: Challenges and Solutions

Tutorial 4 - Monday 22 May, 2006 - 14:00 - 18:00

Delay/Disruption Tolerant Networking

Instructors: Kevin Fall and Michael Demmer (Intel Research, Berkeley and UC Berkeley)

Abstract:

During the past 40+ years, numerous architectures were developed for network communication, with the Internet architecture ultimately emerging as the most influential. These network architectures, including the Internet's, have all been designed with some implicit assumptions about the way applications and the underlying network links will behave. Among the most important assumptions are specific characteristics of the underlying network technologies, such as relatively short transmission delays, low error probability and the existence of end-to-end paths. With the arrival of networking capabilities to portable devices using wireless data communications technology, the desire for interoperability has driven the adoption of pre-existing network communications architectures, and the Internet specifically, into types of operating scenarios where its design assumptions do not hold. This is especially true of ad-hoc and mobile ad-hoc networks that may suffer from long-term outages and rapidly-varying network connectivity. With many of the existing routing protocols assuming end-to-end paths can be found between any sender and intended receiver, sparse ad-hoc networks may operate with either significant inefficiencies or complete loss of connectivity. Several localized, ad hoc solutions attempt to improve specific aspects of the Internet (and other architectures) to better support these types of scenarios, such as applications capable of re-synchronizing after a loss in connectivity. These fixes can be successful in limited scenarios, but often lack broad applicability, i.e., they often address the symptoms of the issues instead of considering the causes. General architectural considerations are needed to approach the issues from a more fundamental and long-term perspective, rather than adding to a growing collection of short-term "patches". Delay and Disruption Tolerant Networking (DTN) is a new area of research in the field of networking that deals with extending existing protocols or inventing new ones in a coordinated, architecturally clean fashion, to improve network communication when connectivity is periodic, intermittent and/or prone to disruptions and when multiple heterogeneous underlying networks may need to be utilized to effect data transfers. Among the challenges of this field of research are large delays (due to either physical distances, small bandwidth, or extended disconnection). A second challenge is efficient routing in the presence of frequently disconnected, pre-scheduled, or opportunistic link availability. A third challenge is high link-error rates that make end-to-end reliability difficult. Finally, heterogeneous underlying network technologies (including non-IP-based internetworks) and application structure and security mechanisms capable of limiting network access prior to data transit are required in environments where feedback may be highly limited. In some cases, an end-to-end path may not exist at any single point in time. From a mobility perspective, DTN relaxes the "always on" paradigm, which would be extremely costly or even impossible to realize in some so-called 'challenged' networking environments. The problems being addressed by DTN extend beyond mobile ad-hoc networks. Several other types of communication scenarios are also being studied, including:

• sparse deployment of wireless base stations
• interplanetary and deep-space communication
• network access in extremely remote areas (e.g., within the polar circle), where regular satellite communication becomes difficult
• network access in developing countries, where no continuously-operating communication infrastructures exist and satellite communication costs are prohibitive
• collecting (massive amounts) of sensor data by means of data mules that are based on occasional short-range, high-bandwidth communication
• enhanced mobility services for nomadic users to effectively deal with connectivity interruptions, e.g., due to gaps in radio coverage or to speed of movement

All the scenarios above constitute uses of "challenged networks" and require new mechanisms to facilitate communications in the respective environments.

Intended Audience

The goal of the tutorial is to review the history and current state of the art in DTN research, present the architecture of the open-source DTN reference implementation, and discuss some of its application scenarios. The tutorial will appeal to persons interested in the following areas:

• characteristics of networks that require special handling
• application areas dominated by or at least benefiting from challenged network support
• research aspects of distributed systems, including naming, routing and scheduling
• operations of data communications networks in remote and difficult-to-reach areas

Biographies of Instructors

Dr. Kevin Fall received his B.A. in Computer Science from the University of California in Berkeley and his M.Sc. and Ph.D. in Computer Science from the University of California, San Diego. He held numerous research and teaching position in networking at the Universities of California in San Diego, Berkeley and Santa Cruz, at MIT, and at Lawrence Berkeley National Laboratory and was co-founder of NetBoost Corporation (an Intel Company). Since 2000, Kevin leads the Delay Tolerant Networking (DTN) research effort at Intel, and is chair of the Delay Tolerant Networking Research Group (DTNRG). DTNRG is a part of the Internet Research Task Force, a companion organization of the Internet Engineering Task Force. As chair of DTNRG, he has been involved in the formulation of DARPA's Disruption Tolerant Networking program, and has been an advisor to its source selection board. He is also working as a Co-PI with Eric Brewer of UC Berkeley, in applying DTN technologies in the context of an NSF-sponsored project to develop information and communication technologies for developing parts of the world such as India, China, and Africa. Kevin was co-chair of the Future Directions in Network Architecture Workshop at SIGCOMM 2004, the co-chair of the Workshop on DTN at SIGCOMM 2005, he is TPC member of Infocom 2005/6 and has served as reviewer for numerous journals and conferences. More information canbe found in http://www.cs.Berkeley.EDU/~kfall

Michael Demmer received his B.S. (w/honors) in Computer Science from Brown University in 1998. After that he held software engineering positions with Tera/Cray Computer, Fast Forward Networks (acquired by Inktomi), and Riverbed Technology. He is now in the PhD program at UC Berkeley working with Prof. Eric Brewer and as a research intern with Dr. Kevin Fall of Intel Research Berkeley. At Intel, he has been leading the design and implementation of the DTN reference implementation. Please visit http://www.cs.Berkeley.EDU/~demmer for more details.

Tutorial 5 - Monday 22 May, 2006 - 9:00 - 13:00*****CANCELED*****

Design Guidelines for Network Layer Protocols in Sensor and Ad Hoc Networks

Tutorial 6 - Monday 22 May, 2006 - 9:00 - 13:00

Multimedia Conferencing in Mobile Ad Hoc Networks: Challenges and Early Approaches

Instructors: Roch H. Glitho, (LM Ericsson and Concordia University)

Abstract:

Mobile ad hoc networks (MANETs) are infrastructure-less and can be set up anywhere, anytime. They can host a wide range of applications in military, disaster recovery, commercial and private settings. Many of these applications rely on multimedia conferencing. Some examples are voice/video conferencing, massively multiplayer games and distance learning. Multimedia conferencing can be defined as the conversational exchange of multimedia content between at least three parties. It is made up of two main components: signalling and media handling. The signalling component sets up, modifies and tears down conferences. The media handling part deals with aspects such as mixing and trans-coding. This tutorial identifies the challenges associated with multimedia conferencing in MANETs, pinpoints the shortcomings of the traditional approaches, and introduces the novel approaches that are now emerging. The peculiarities of MANETs put very stringent requirements on signalling and media handling. An example is that none of the involved entity should be centralized, seeing that MANETs are infrastructure-less by definition. Another example is high scalability MANETs may have thousands of nodes in military settings. Yet another example is that resources should be used in an optimal way because of the heterogeneity of MANET nodes. We introduce the traditional approaches to signalling for multimedia conferencing proposed as part of the general signalling systems such as the IETF Signalling Initiation Protocol (SIP), and the ITU-T H.323, and show that none of them is suitable for MANETs. We also introduce the traditional media handling systems (e.g. centralized mixing, end-to-end mixing) and show as well that none of them meets the stringent requirements of MANETs. Novel signalling and media handling approaches dedicated to MANETs are now emerging, although they are still very few. We discuss them extensively and show that the most promising rely on application level clusters and overlay networks.

Intended Audience

This tutorial is intended for researchers and engineers from academia and industry who are interested in (or just curious about) application layer issues in MANETs, especially multimedia conferencing. Multimedia conferencing is a very rich research area which illustrates quite well many of the challenges faced by the application layer of MANETs. The attendees should have as pre-requisite an undergraduate level knowledge of communication networks and protocols.

Biography of Instructor

Roch H. Glitho [SM] (http://www.ece.concordia.ca/~glitho/) holds a Ph.D. (Tekn. Dr.) in tele-informatics (Royal Institute of Technology, Stockholm, Sweden) and M.Sc. degrees in business economics (University of Grenoble, France), pure mathematics (University Geneva, Switzerland), and computer science (University of Geneva). He works in Montreal, Canada, as an Expert in service engineering at Ericsson, and as an Adjunct Associate Professor at Concordia University. In the past he worked as a Senior Specialist in network management for Ericsson Telecom in Stockholm, and as an R&D engineer for a computer manufacturer in Oslo, Norway. His industrial experience includes research, international standards setting (e.g. contributions to ITU-T, ETSI, TMF, ANSI, TIA, and 3GPP), product management, project management, systems engineering and software/firmware design. He is an IEEE distinguished lecturer, a senior technical editor of IEEE Communications Magazine and a technical editor of the Journal of Network and Systems Management (JNSM) published by Springer. In the past he has served as the Editor-In-Chief of IEEE Communications Magazine and IEEE Communications Surveys & Tutorials Magazine. His research areas include architectures for end-users services, signalling, network management and mobile code. In these areas, he has authored around 50 peer-reviewed papers, more than fifteen of which have been published in well-known refereed journals. He has also guest-edited some 10 special issues of refereed journals and has more than 20 patents in the aforementioned areas.